Title 21 United States Code (USC) Controlled Substances Act classifies cannabis as a controlled substance.
How is it possible for states to legalize a substance which is illegal according to federal law? Couldn't the FBI and DEA enforce federal law and arrest marijuana traders and consumers in Colorado and Washington?

You should reference the "already written" law you are talking about. The more specifics you can give,me better answers you will get.
– rougonSep 4 '16 at 19:08

I rewrote your question to better fit the tone of this website.
– Philipp♦Sep 4 '16 at 20:06

@Philipp, but the title doesn't suite the question. My question is about the feds not enforcing existing laws and not whether states can legalize it since they somehow did (even though it violated federal law).
– NoahSep 4 '16 at 20:14

@Rathony I think that questions about if, how, why and why not the federal government gets involved in state decisions is very on-topic here.
– Philipp♦Sep 5 '16 at 19:45

3 Answers
3

You should note the following big differences when it comes to medical or recreational marijuana.

They are legal under the state law. The amount for its sales or prescription is controlled and monitored by the state government.

FBI and DEA have higher-priority and more serious problems to deal with such as cocaine, heroine, methamphetamine, etc. State-approved marijuana trade and consumption have far lower-priority than other substances.

It is wrong to assume that all the state laws should always be in line with the federal laws. Most of the time, the state laws are based on the federal laws, and when a state law is in direct conflict with federal law, the federal law prevails. The problem is it takes a lot of time and money to settle this conflict through lawsuit. The current administration has more liberal point of view on medical and recreational use of marijuana and how and when to enforce the federal law will depend much on the position of the federal government. In other words, it can be more vigorously enforced if the position of the federal government changes.

From the federal government's point of view, as long as consumption, distribution and amount of marijuana, etc. are controlled in a state, they seem to be reluctant to prosecute those involved in the business using the federal law as they contribute a lot to tax revenue for the federal and state governments creating jobs and increasing GDP. Of course, they will enforce the law if a patient or buyer, in possession of marijuana, goes into a state where medical or recreational marijuana is still illegal. It all boils down to cost against benefit. As long as benefit outweighs cost from the federal and state governments' point of view, the federal government is less likely to enforce the federal law.

"It would not make sense for us to see a top priority as going after recreational users in states that have determined that it's legal," he said, invoking the same approach taken toward users of medicinal marijuana in 18 states where it's legal.

By the way: I asked about how the twocandidates for Obama's succession see the issue, and it seems they both agree with him that the federal agencies should not interfere with state-level legalization of marijuana.
– Philipp♦Sep 5 '16 at 16:22

The federal government only has the right to regulate drugs via the very broad and encompassing Commerce Clause of the US Constitution. Their right to intervene in the legalization of marijuana if it is produced, regulated, taxed and consumed all within any given state's borders will probably be revisited, since the very tenuous and broad definition used to issue the ruling in Gonzalzez vs Raich doesn't hold up very well under scrutiny.

Also, given national opinions on this substance, and actual medical science, it is highly unlikely that the classification of marijuana as a Schedule I drug - along with heroin, which does not even apply to dangerous drugs like cocaine, PCP or methamphetaine, will continue to be in place for the forseeable future.